DE 101 41 432 A1 discloses a suspension spring unit comprising two leaf springs which are formed from a weight-minimizing fiber composite material. The suspension spring unit is constructed from two leaf spring elements which comprise an arch, wherein the inner sides of the arch of the leaf springs face each other. End connecting elements via which the two leaf springs are connected to each other are located at the spring ends of the leaf springs. It is specified here that at least two leaf springs composed of fiber composite material can form the suspension spring unit, wherein, in the case of a construction of more than two leaf springs, the latter, instead of a single-layered design, can be arranged stacked on one another in multiple layers and can be connected to one another via the end connecting elements. A resulting stacked construction of leaf spring elements produced at least from a steel material is known, for example, from the manufacturing of utility vehicles.
In order to arrange the suspension spring unit between a vehicle body and a wheel carrier, central connecting elements in the form of screw pins are located in the central regions of the leaf springs, and therefore the upper leaf spring and the lower leaf spring can be screwed to the vehicle body and to the wheel carrier, respectively.
During operation of such a leaf spring unit, a minimum spring deflection is required, and stoppers are proposed which are attached on the inside in the region of the central regions to the leaf springs such that the opposite stoppers can strike against each other as stops when the suspension spring unit is subjected to a compressive force, as a result of which the maximum spring deflection is greatly restricted.
Disadvantageously, transverse forces can be absorbed by the shown construction of the suspension spring unit only to a reduced extent since an oblique load on the leaf spring pair may rapidly lead to failure of the suspension spring unit. In particular, in the case of the shown construction, the possibility does not arise of the leaf spring pair being able to bend laterally outward, and, because of the required relatively large spring deflection in use in a vehicle chassis, a great length is required in the transverse direction of the leaf springs that runs perpendicularly to the spring direction. The spring direction is defined here by the positions of the central connecting elements which are shown. A multi-layered configuration of the leaf springs in a packet arrangement, which leaf springs, mounted in a stacked manner, in the case of the shown bilateral arch direction of the leaf springs, are connected to each other with the inner side of their arch via the end connecting elements, kinetic energy not required in the suspension spring unit in conjunction with a shock absorber as the suspension spring unit for a vehicle chassis can be dissipated.